The present invention relates to a communication device for an automatic vending machine, in which communication is carried out by a contention type protocol.
A plurality of terminal control units each of which controls each unit such as a customer service unit or a vending unit, and a main control unit which collectively controls the terminal control units are installed in an automatic vending machine. A plurality of terminal control units is set to the predetermined specification and implements a series of vending actions by communication with the main control unit.
A communication system such as a polling type protocol or a contention type protocol is mainly used between the main control unit and the terminal control systems. The main control unit has a prior transmission right in the polling type protocol. That is, the main control unit asks each terminal control unit one by one if it requests a transmission, and only when each terminal control unit requests the transmission, the terminal control unit transmits a data to the main control unit. On the other hand, the main control unit and the terminal control unit have equal transmission rights in the contention type protocol. In a case where either the main control unit or the terminal control units request a transmission prior to the other, one transmits data to the other.
The contention type protocol has been currently used as a communication system between the main control unit and the terminal control units, because a communication time for the data transmission from the terminal control units to the main control unit is shorter in the contention type protocol than in the polling type protocol. An automatic vending machine implementing communication in accordance with the contention type protocol is disclosed in Japanese Patent Application No. 223823/1998 filed by the applicant.
In the Japanese Application No. 223823/1998, an automatic vending machine has a plurality (generally, several tens units) of button control units as a terminal control unit. A plurality of the button control units controls a plurality of item selection buttons which are installed on a front surface of the automatic vending machine. However, under the contention type protocol, if the item selection button is pressed, communication is carried out between the main control unit and the terminal control units, regardless of the situation. For example, in the presence or absence of sold-out display or in the presence or absence of sales possible display, the corresponding button control units always transmit some data to the main control unit. As a result, the button control units transmit meaningless data to the main control unit. This causes such problems that incorrect operations and incorrect vending occur.
An object of the invention is to provide a communication device for automatic vending machine in which the main control unit can select communication functions of the terminal control units.
This and other objects of the invention can be attained by a communication device for an automatic vending machine having a plurality of terminal control units. Each terminal control unit controls each unit of the automatic vending machine. A main control unit controls the terminal control units. Contention type protocol is used for communication among the main control unit and the terminal control units, where they have equal transmission rights. The main control unit transmits to the terminal control units, a control data that allows or prohibits transmission from the terminal control units at a predetermined timing and the terminal control units set an inside of the terminal control units to the conditions corresponding to the control data. According to the first embodiment of the invention, incorrect operations and incorrect vending can be prevented because some of the terminal control units are set to have the transmission right and the other terminal control units are set not to have the transmission right.
In one aspect of the present invention, the predetermined timing is when the automatic vending machine is initialized by an introduction of electric power. According to this aspect, the terminal control units can be set to the functions corresponding to the specification of each automatic vending machine simultaneously when the electric power is turned on.
In another aspect of the present invention, the terminal control units are plural button control units which control a plurality of item selection buttons.
In a further aspect of the present invention, the control data includes contents to allow or prohibit transmission from the button control units to the main control unit when the item selection buttons are pressed.
In another aspect of the present invention, the control data includes contents to allow or prohibit transmission from the button control units to the main control unit when the item selection buttons are pressed in the state that xe2x80x9csold outxe2x80x9d is displayed.
In another aspect of the present invention, the control data includes contents to allow or prohibit transmission from the button control units to the main control unit when the item selection buttons are pressed in the state that xe2x80x9csales possiblexe2x80x9d is displayed.
In a further aspect of the present invention, some of the button control units are set to have the transmission right and the other button control units are set not to have the transmission right in accordance with sorts of the item selection buttons and presence or absence of xe2x80x9csold outxe2x80x9d and xe2x80x9csales possiblexe2x80x9d display.